Yoav Bashan

Scientific cartoons

The artwork in this segment can be used by students and researchers for scientific presentations and publication free of charge, providing they notify the Bashan Foundation and a proper citation of the artist is provided during the presentation

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RThis cartoon was presented in the11th International Plant Growth-Promoting Rhizobacteria Workshop, June 17-21, 2018 – Victoria, British Columbia, Canada as part of an invited lecture by Yoav Bashan on "Restoration of degraded soils by plant growth-promoting bacteria".

Graphic design and computer execution: Gerardo Hernandez Garcia
Idea and general planning: Yoav Bashan.


Resource islands provide a safe heaven for plants to grow in the desert. Usually it happens under the canopy of a legume “nurse tree”. The resource island contains a large number of micro- and macro organisms, better water conditions, improve nutrition for plants and shadow from strong desert sun. In the Sonoran desert young plants rarely grow in open lands. This cartoon was produced for a chapter in popular science book to be published in 2012 entitled “de-Bashan, L.E., Vazquez, P., Lopez, B.R., Moreno, M., Hernandez, J.-P., Bacilio, M., Leyva, L.A., and Bashan, Y. 2012. Los mas pequeños y los mas grandes:¿Qué los microorganismos ayudan a las plantas del desierto? In: ¿Qué se mueve en el desierto?: la palpitante vida del matorral. (Eds): de la Luz, J.L. and Blazquez, C. Published by: CIBNOR, La Paz, Mexico”.

Graphical design and computer execution: Patricia Vazquez
Idea and general planning: Yoav Bashan.


Joint immobilization of the microalgae Chlorella and the plant growth-promoting bacteria Azospirillum used as agents for wastewater treatment in polymer alginate beads provides them essential protection against predatory organisms residing in wastewater. This work was presented in: Cruz I., Hernandez J.-P., de-Bashan L.E. and Bashan Y. 2011. Removal of nutrients from domestic wastewater in autotrophic and heterotrophic 50-L bioreactors using the microalgae Chlorella vulgaris and the bacterium Azospirillum brasilense jointly immobilized in alginate beads. In: The 4th Congress of the International Society for Applied Phycology, 19–24 June 2011, Halifax, Canada.

Only a combination of several ammendments (Azospirillum, phosphate-solubilizing bacteria, myccorrhizae fungi, and compost) to degraded arid soil is capable of reversing low soil fertility to a level that allows native desert trees to prosper where they could not grow before. This work was presented in: Bashan Y., Puente E., Salazar B., Bacilio M. 2007. Azospirillum as a “team player” in preventing and restoring desert soil erosion. In: Azospirillum VII and related PGPR International Workshop. August 31–September 1, 2007. Montpellier, France.

The contribution of the plant growth-promoting bacteria Azospirillum spp. to the microalgae Chlorella spp. is probably hormones that activate its metabolic pathways and cause the microalgae to absorb more ammonium and phosphorus. 2007. This work was presented in: de-Bashan L.E., Hernandez J.P., Bashan Y. 2007. Azospirillum brasilense as an enhancer of wastewater treatment with the microalgae Chlorella spp., a novel biotechnological application. In: Azospirillum VII and related PGPR International workshop. August 31–September 1, 2007. Montpellier, France and in: de-Bashan, L.E., Bashan Y. 2007. Azospirillum and green microalgae: a convenient model for basic studies of plant-bacterium interactions. In: First International Workshop in Azospirillum: Cell Physiology, Plant Response and Agronomic Research in Argentina 2007. October 12–13, 2007. Córdoba, Argentina.

The giant cardon cactus growing in rocks in the absence of soil depends solely on many types of bacteria where each has a role in degrading the rocks—some dissolve the rocks, some solubilize phosphate and other essential minerals, some fix nitrogen, and some transport minerals to the plant roots. In such an efficient system, the plants flourish without benefit of soil. 2003. This work was presented in: Puente, M.E., Li, C.Y. and Bashan, Y. 2003. Rock weathering, plant growth-promoting bacteria from desert plants allow the growth of cactus seedling in rocks. Sixth International PGPR Workshop.5-10 Oct. 2003, Kozhikode (Calicut), India.

Recruitment poster for potential male graduate students for the Environmental Microbiology Group at CIBNOR in La Paz, Mexico. 2001. This work is presented on the Group’s website:
http://www.bashanfoundation.org/gmaweb/istudecon.html

Recruitment poster for potential female graduate students for the Environmental Microbiology Group at CIBNOR in La Paz, Mexico. 2001. This work is presented on the Group’s website:
http://www.bashanfoundation.org/gmaweb/istudecon.html

When the microalga Chlorella is artificially associated with the microalgae growth-promoting bacteria Azospirillum in treatment of wastewater, the bacteria enhances absorption of contaminants (phosphorus and nitrogen) by the microalga to a greater extent. 2000. This work was presented in: Gonzalez, L.E. and Bashan, Y. 2000. Environmental applications of plant growth-promoting bacteria. Tenth International Conference on Plant Pathogenic Bacteria. 23-27 July 2000. Charlottetown, Canada.

The role of the mangrove microbial community in supporting the fishing industry. Many type of beneficial microorganisms residing in the roots are helping the trees to grow. The trees in turn support almost all of tropical marine life that are the basis of the fishing industries. This work was published in: Holguin, G., Bashan, Y., Mendoza-Salgado, R.A., Amador, E., Toledo, G. Vazquez, P. and Amador, A. 1999. Microbiology of mangroves, forests in the frontier between land and sea. Ciencia y Desarrollo 25 (no.144): 26-35 (Painted with the help of Gina Holguin)

The contribution of mangroves to young marine life is that they provide protection and food to animals in their initial life stages, allowing them to grow large enough to fend for themselves in the open water. This work was published in: Holguin, G., Bashan, Y., Mendoza-Salgado, R.A., Amador, E., Toledo, G. Vazquez, P. and Amador, A. 1999. Microbiology of mangroves, forests in the frontier between land and sea. Ciencia y Desarrollo 25 (No.144): 26-35. (Painted with the help of Gina Holguin)

The contribution of the bacterial community to phosphorus nutrition of mangroves is that some bacteria contribute to disruption of the phosphate rock and some bacteria produce acids that dissolve the rock. The available dissolved phosphate is absorbed by the tree as a nutrient. This work was published in: Holguin, G., Bashan, Y., Mendoza-Salgado, R.A., Amador, E., Toledo, G. Vazquez, P. and Amador, A. 1999. Microbiology of mangroves, forests in the frontier between land and sea. Ciencia y Desarrollo 25 (No.144): 26-35. (Painted with the help of Gina Holguin)

The contribution of mangroves to the bacterial communities’ well being is the abundance of root exudates and organic matter as a nutrient. This fuels intensive microbial activities of numerous beneficial micro-organisms that help the trees grow better. This work was published in: Holguin, G., Bashan, Y., Mendoza-Salgado, R.A., Amador, E., Toledo, G., Vazquez, P., and Amador, A. 1999. Microbiology of mangroves, forests in the frontier between land and sea. Ciencia y Desarrollo 25 (No.144): 26-35. (Painted with the help of Gina Holguin)

Despite all efforts and assisted treatments (common in plant pathology to help a bacterial pathogen to enter the host plant) to assist the plant growth-promoting Azospirillum to damage its host plants, Azospirillum remains a harmless bacterium that mostly contributes beneficial hormones to the plants and nothing else. 1997. This work was presented in: Alcaraz-Melendez, L., Real-Cosio, S., Amador, A., and Bashan, Y. 1997. Evidence for harmlessness and deleterious effects of Azospirillum spp. inoculation on plants. In: Fourth International Workshop on Plant Growth Promoting Rhizobacteria. 5-10 Oct. 1997, Sapporo, Japan.

A crucial question that any farmer or inoculant scientist asks is: How long will inoculation with the plant growth-promoting bacteria Azospirillum last? Most studies indicate seasonal survival of the inoculant, but sometimes survival for years has been recorded. 1997. This work was presented in: Bashan, Y. and Holguin, G. 1997. Short- and medium term avenues for Azospirillum inoculation. In: Fourth International Workshop on Plant Growth Promoting Rhizobacteria. 5-10 Oct. 1997, Sapporo, Japan.

The plant growth-promoting bacteria Azospirillum is a rhizosphere bacteria (root dweller). A main issue: Does it survive in soils in the absence of plants? Answer: Not well. 1997. This work was presented in: Bashan, Y. and Rojas, A. 1997. Improved establishment and development of three cactus species in eroded urban soils by inoculation with Azospirillum brasilense. In: First National Congress on Cacti. 26-29 Nov. 1997, Montecillo, Mexico

The interaction between the plant growth-promoting bacteria Azospirillum and its host plant can be light, tight, or no interaction at all. 1997. This work was presented in: Castellanos, T., Ascencio, F. and Bashan, Y. 1997. Bacterial cell-surface hydrophobicity, charge and lectins as a possible means for the initial attachment of Azospirillum spp. to surfaces. In: Fourth International Workshop on Plant Growth Promoting Rhizobacteria. 5-10 Oct. 1997, Sapporo, Japan.

The main reason for studying plant growth-promoting bacteria is that they are cheaper than the fertilizers they could replace. This work was presented in: Bashan, Y., Carrillo, A., and Holguin, G. (1995) New synthetic and multi-species bacterial inoculants for plant growth-promoting rhizobacteria. In: Tenth International Congress on Nitrogen Fixation. 28 May-5 June 1995, St. Petersburg, Russia.

When inoculating plants with plant growth-promoting bacteria, more bacteria are not necessarily better. 1995. This work was presented in: Bashan, Y. 1995. Azospirillum and other non-biocontrol PGPR: Do they have a place in the agricultural future of developed countries? In: BIOREM Meeting of Canadian Biotechnologists. 16-17 March 1995, Vancouver, Canada.

The fundamental question of inoculation of plants with plant growth-promoting bacteria in the field; Do the bacteria survive? Do they multiply? Or do they perish? 1995. This work was presented in: Bashan, Y., Carrillo, A., and Holguin, G. 1995. New synthetic and multi-species bacterial inoculants for plant growth-promoting rhizobacteria. In: Tenth International Congress on Nitrogen Fixation. 28 May-3 June 1995, St. Petersburg, Russia

Always, the end-product of any technology is “bright” and usually far, far away. This work was presented in: Bashan, Y. (1995) Azospirillum and other non-biocontrol PGPR: Do they have a place in the agricultural future of developed countries? In: BIOREM Meeting of Canadian Biotechnologists. 16-17 March 1995, Vancouver, Canada

The fundamental question of inoculation of plants with plant growth-promoting bacteria in the field is: Do bacteria reach their target plants despite many physical barriers and large numbers of predators and competitors? 1995. This work was presented in: Bashan, Y. and Holguin, G., 1995. Ecological soil factors affecting the inoculation of plants with beneficial bacteria. In: First International Meeting on Microbial Ecology. 8-12 May 1995, Mexico City

What kind of possible inoculants are available for plant growth-promoting bacteria? There are several options. This work was presented in: Bashan, Y., and Carrillo, A. (1994) Bacterial inoculants for sustainable agriculture. In: Second International Symposium on Agroecology, Sustainabilty and Education. 16-18 November 1994. San Luis Potosi, Mexico

Neighboring plants and even weeds are helping the plant growth-promoting bacterium Azospirillum to colonize many plants in the surrounding areas. 1994. This work was presented in: Bashan, Y., Holguin, G., Rodriguez, N. Puente, M.E. and Ferrera-Cerrato, R. 1994. Azospirillum brasilense: root colonization of weeds and crop plants, inter-root movement and survival in soils and rhizosphere. In: Fifteenth World Congress of Soil Science, 10-16 July 1994, Acapulco, Mexico

When inoculated into soil without plants, the plant growth-promoting bacterium, Azospirillum, is adsorbed strongly and irreversibly by soil particles and perishes within a short period of a few weeks. 1994. This work was presented in: Bashan,Y., Puente, M.E., Rodriguez-Mendoza, M.N., Holguin, G., Ferrera-Cerrato, R., Toledo, G. and Pedrin, S. 1994. Soil parameters which affect the survival of Azospirillum brasilense. In: NATO Advanced Research Workshop on Azospirillum and Related Micro-organisms. 4-7 Sept. 1994, Sarvar, Hungary.

Fibrillar material produced by the plant growth-promoting Azospirillum is essential for the survival of the cells in sand. Without them, the cells are eluviated to deeper soil layers below root areas and perish. 1994. This work was presented in: Bashan, Y., Carrillo, A., and G. Holguin. 1994. Rhizosphere dispersion of the biofertilizer Azospirillum brasilense. Third International Workshop on Plant Growth-Promoting Rhizobacteria.7-11 March 1994, Adelaide, Australia

Are there specific attractants than govern chemotaxis (movement towards chemicals) of the plant growth-promoting bacterium Azospirillum towards plants? 1994. This work was presented in: Bashan, Y., Carrillo, A. and G. Holguin. 1994. Rhizosphere dispersion of the biofertilizer Azospirillum brasilense. Third International Workshop on Plant Growth-Promoting Rhizobacteria.7-11 March 1994, Adelaide, Australia

The important role of chemical attractants and repellants in the migration of the plant growth-promoting Azospirillum from heavily-colonized plant roots to neighboring plants, making the entire field colonized by these bacteria. 1994. This work was presented in: Bashan, Y., Carrillo, A. and G. Holguin. 1994. Rhizosphere dispersion of the biofertilizer Azospirillum brasilense. Third International Workshop on Plant Growth-Promoting Rhizobacteria.7-11 March 1994, Adelaide, Australia

The mangrove bacterium Staphylococcus, when mixed with the plant growth-promoting Azospirillum, caused the latter to fix more atmospheric nitrogen. 1992. This work was presented in: Holguin, G. and Bashan, Y. 1992. Increasing the nitrogen-fixing activity of Azospirillum by mixed culturing with Staphylococcus sp. Ninth International Congress on Nitrogen Fixation. 6-12 Dec. 1992, Cancun, Mexico

Despite earlier claims that the plant growth-promoting Azospirillum is beneficial mainly to cereals, it seems that this bacteria has general beneficial bacteria to most plant species and has the capacity to recognize and enhance the growth of all. 1992. This work was presented in: Bashan, Y., Holguin, G., Puente, E., Carrillo, A., Alcaraz-Melendez, L., Lopez-Cortes, A., and Ochoa, J.L. 1992. Current status of Azospirillum inoculation technology. Eighth Eastern Europe Symposium on Biological Nitrogen Fixation. 22-26 Sept. 1992, Saratov, Russia.

As with any technology developed in the laboratory, one eventually reaches the application phase. The problem is now, how to inoculate plant growth-promoting bacteria in the field? This work was presented in: Bashan, Y., Holguin, G., Puente, E., Carrillo, A., Alcaraz-Melendez, L., Lopez-Cortes, A., and Ochoa, J.L. (1992) Current status of Azospirillum inoculation technology. Eighth Eastern Europe Symposium on Biological Nitrogen Fixation. 22-26 September 1992, Saratov, Russia

Measuring plant response to inoculation with the plant growth-promoting bacteria Azospirillum is never an easy task. 1991. This work was presented in: Puente, M.E., and Bashan, Y. 1991. Differential responses of seeds and seedlings of the Cardon cactus to inoculation with Azospirillum brasilense. Fifth International Workshop on Azospirillum and Related Microorganisms, 4-7 Sept. 1991, Wennigsen/Deister, Germany.

There are plenty of bacteria in the soil. However, how do you define the good ones? This work was presented in: Levanony, H. and Bashan, Y. (1990) Active attachment of Azospirillum brasilense to root surface and to soil particles. Fourth International Symposium on Nitrogen-Fixation with Non-legumes, 10-14 September 1990. Florence, Italy

The plant growth-promoting Azospirillum needs an active mechanism to allow attachment to sand particles. 1990. This work was presented in: Levanony, H. and Bashan, Y. 1990. Active attachment of Azospirillum brasilense to root surface and to soil particles. Fourth International Symposium on Nitrogen-Fixation with Non-legumes, 10-14 Sept.1990, Florence, Italy.

When a plant is colonized by beneficial bacteria, the main question is where are the bacteria? This work was presented in: Bashan, Y. and Levanony, H. (1987) Bacteria-root cell interaction during primary stages of wheat root colonization by Azospirillum brasilense Cd. Fourth Azospirillum Workshop, June 17-18, 1987, Bayreuth, Germany

Regardless of the physiological properties of the plant growth-promoting Azospirillum to enhance plant growth, a major role for its effect on plant is its capacity to firmly attach to the roots. 1987. This work was presented in: Bashan, Y. and Levanony, H. 1987. Bacteria-root cell interaction during primary stages of wheat root colonization by Azospirillum brasilense Cd. Fourth Azospirillum Workshop, 17-18 June 1987, Bayreuth, Germany

A research team is always far larger than the person who is presenting the talk at a conference and they usually are staying in the “shadows.” This work was presented in: Bashan, Y. and Levanony, H. (1986) Root-bacteria interaction and its possible role in establishing a beneficial association. Interlec-8, Eighth International Lectin Meeting, 26-30 May 1986, La Paz, Baja California Sur, Mexico.

Root tips that grow very quickly can transfer the plant growth-promoting bacteria Azospirillum to depths far exceeding the inoculation site—a major advantage for the inoculation industry. 1986. This work was presented in: Bashan, Y. and Levanony, H. 1986. Root-bacteria interaction and its possible role in establishing a beneficial association. Interlec-8, Eighth International Lectin Meeting, May 26-30, 1986, La Paz, B.C.S., Mexico.

Upon inoculation, the plant growth-promoting bacteria Azospirillum faced tough competition from the microorganisms in the soil. It is possible by adding some chemicals to which the plant growth-promoting bacteria are resistant and the competitors are not to suppress for short period of time the competition. This allows the plant growth-promoting bacteria Azospirillum to become established in the rhizosphere of the host plant. 1986. This work was presented in: Bashan, Y. and Levanony, H. 1986. Association between wheat root and Azospirillum in relation to root colonization. Fourth International Symposium on Microbial Ecology, August 24-29, 1986, Ljubljana, Yugoslavia.

Even when plant growth-promoting bacteria are inoculated into the soil close to the plant, the actual distance the bacteria should move through the soil layers, with its numerous obstacles, is far larger than the direct distance. 1985. This work was presented in: Bashan, Y., Levanony, H., Filon, D., and Ben-Yehuda, A. 1985. Motility of rhizosphere bacteria in the soil towards wheat roots. The Thirteenth Aharon Katzir-Katchalsky Conference on Sensing and Response in Microorganisms. March 17-22, 1985, Ayelet Hashachar, Israel.

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